Windows server 2008 or 2011

I had near the same dilemma a few years back, and now I have the opportunity to get a server and some client computers for cheap from an office closing. I'm being offered either a dual core work station that have windows server 2008 loaded or a quad core server with server 2011 small business. Then some workstations with windows 7. I pretty much need some advice and path of direction, because I'm beyond rusty with server 2008, and 2011 I only helped a friend installed it a while back. What I want accomplished is to be able to do the following:

Log off one workstation as a certain user account then log back on through another workstation with the same account and have access to all my previously saved work. (maybe virtualization?)

have certain network drives setup for each user account

Setup a vpn to synchronize certain folders.

Have the user accounts and data on the server.

setup printing limits.

Pretty much Even though I'm not there yet in the real world I'm trying to emulate an office network. Currently, I have 2 routers and a switch. The main router has on dd-wrt and handles dhcp, and the other router is pretty much an extension. Any advice and help is appreciated.

The quad core is a good 300 more. Its I think a 3.2, I have to look back at my notes and it's a xeon, but I was thinking if I can get the dual core to do exactly what I need then it would be my choice since it's cheaper. I had a friend that is an IT give me this trainsignal windows server 2008 program for learning server 2008. I've installed it but havent gotten a chance to look at it. Unfortunately since he is in an apprenticeship he gave me everything he knew but it got me only so far since he is familiar with only 2003 and 2008. Is there any topics I should be directly looking at with this software?

Pretty much for what I'm looking for is it possible? Can I also create "guest" like accounts that have no access to certain items and will not attach all drives? Do I have to install the programs on the local computer, or should I install them on the server? Is this something I should do in another os like linux? I was thinking windows server since its pretty much a windows network, and since it's being included.